Hydrogenation of steam cracked gasoline



United States harem 3,024,188 HYDROGENATION OF STEAM CRACKED GASOLINE Alan Arthur Yen and John Norman Haresnape, Sunburyoil-Thames, England, assignors to The British Petroileum Company Limited, London, England, a jointstock corporation of Great Britain No Drawing. Filed Aug. 27, 1958, Ser. No. 757,446 Claims priority, application Great Britain Sept. 6, 1957 19 Claims. (Cl. 208-464) This invention relates to an improved process for the partial hydrogenation of unsaturated gasolines.

It is known that some gasolines, for example gasolines obtained by steam cracking, contain gum forming constituents which impair the value of this material as a blending component for motor fuels.

It is an object of this invention to provide a process for improved unsaturated gasolines by hydrogenation. It is a further object to provide a process for improving the gum stability of gasolines. Other objects will appear hereinafter.

According to the present invention there is provided a method for improving a gasoline containing at least one diolefin and/or at least one styrene, which comprises passing said gasoline with hydrogen over a supported elemental nickel catalyst under conditions such that diolefins, if present, are hydrogenated to mono-olefins, and styrenes, if present, are hydrogenated to saturated side chain aromatics.

Preferably the severity of the conditions of hydrogenation is selected to provide a high percentage conversion of any diolefines present to mono-olefins and of any styrenes present to saturated side chain aromatics with a low percentage conversion of acyclic mono-olefins and of diolefins to saturated hydrocarbons. As is well known in the art, severity of hydrogenation can be increased by raising the hydrogen partial pressure, raising the reaction temperature, increasing the hydrogen/feedstock ratio or decreasing the flow rate.

According to a further feature of this invention it has now been found that the gum stability of a gasoline containing diolefins and/or styrenes, for example, a steam cracked gasoline, may be improved by hydrogenation over a supported elemental nickel catalyst, with only a small loss of octane number, by control of the amount of hydrogen thereby combined with unit weight of the gasoline feedstock. Thus according to this further feature of the invention there is provided a process which comprises continuously passing a gasoline which contains at least one diolefin or at least one styrene, said gasoline being, for example, a steam cracked gasoline which contains gum forming constituents, with hydrogen over a supported elemental nickel catalyst under hydrogenation conditions, the amount of hydrogen thereby combined with unit weight of the gasoline feedstock being controlled at a predetermined value such that the octane number, as hereinafter defined, of the product is at least as great or not substantially less than that of the gasoline feedstock.

Steam cracked gasolines not only contain such gum forming constituents as diolefins or styrenes, but are characterized further by the fact that they contain sulfur compounds. In the past, it has generally been recognized that sulfur-containing feed stock is unsuitable for use over an elemental nickel catalyst when the object is to achieve hydrogenation of dienes at low temperature. Un-

expectedly and surprisingly, however, the steam-cracked gasolines described herein do not de-activate the elemental nickel catalyst. On the contrary, the elemental nickel catalyst of the present invention remains highly active for long periods of time in achieving selective hydrogenation of the dienes contained in these gasolines which have been cracked at high temperatures.

The desired amount of hydrogen to be combined with unit weight of the gasoline feedstock may be predetermined on the basis of a series of simple test runs. Thus it will be found that as this amount of hydrogen increases from zero value, the gum stability of the product will improve. Up to a certain amount of hydrogen (per unit weight of gasoline) this improvement will increase with increase in this amount of hydrogen and without substantial loss of octane number (between feedstock and product), while beyond this value there will be an increasing loss of octane number with increase in this amount of hydrogen; the optimum amount of hydrogen per unit weight of a given gasoline feedstock will be apparent from a series of tests covering a range of values. Control of the amount of hydrogen combined may be effected by variation of the reaction temperature, or reaction pressure or hydrogen/ gasoline feedstock ratio.

The amount of hydrogen combined with unit weight of gasoline feedstock can be determined by measurement of the flow rate of hydrogen recovered in the process (flow rate of hydrogen in the feed gas and gasoline feed rate being known).

Gum stability may be measured by any of the methods known in the art, the Lauson rating being a very suitable method. The Lauson test is described in The Petroleum Engineer, vol. 27 at pages 019-030 (November 1955).

Octane number of the product of test runs may be determined by any of the methods known in the art; the scale for the purpose of the present invention is a measurement of the unleaded octane number by the octane number (research) method as described in the ASTM Manual for Rating Motor Fuels by Motor and Research Methods (1956).

The process of the present invention is suitable for treatment of gasolines boiling within the range 15 C. to 200 C. Suitably the gasolines are debutanised materials. Preferably the gasolines are free of hydrogen sulphide. Preferably the gasolines treated in accordance with the present invention have a total sulphur content of 0.005 to 0.04% by weight. The gasolines may be produced by cracking, in the presence of steam, petroleum distillate fractions, for example primary flash distillate or naphthas, boiling within the range 15 C. to 250 C. Particularly has the process of the invention been found to be beneficial in the treatment of gasolines produced by steam cracking under conditions favouring the production of olefins. Suitable cracking temperatures lie in the range 1100 F. to 1400 F. and suitable cracking pressures lie in the range 0 to 50 lbs/sq. in. gauge.

By the term supported elemental nickel catalyst we mean a catalyst which, after reduction, consists of elemental nickel on a catalyst base.

A preferred catalyst is elemental nickel-on-alumina. Preferably the alumina is present as gamma alumina.

Suitable elemental nickel-on-alumina catalysts are prepared by the impregnation of solid alumina, in the form of wet or dry alumina gels, with a solution of an easily decomposable nickel salt, e.g. nitrate, acetate, formate, followed by drying the mixture and roasting at 500 C.

for 2 hours. A typical catalyst containing 10% nickel by weight of the finished catalyst is obtained by impreg- Operating conditions are preferably selected to ensure that the hydrogen partial pressure is at least 100 lbs/sq.

nating 400 grams of Ms" (one eighth inch) alumina in. gauge.

pellets wtih a solution of 220 grams of nickel nitrate Preferred operating temperatures lie in the range 80 hexahydrate in 75 ml. of water. The mixture is dried 5 180 C. l

at 140 C. for 8-16 hours and roasting at 500 C. for 2 Gas is preferably separated from the liquid product hours. at a temperature below 40 C.

Preferably, however, the elemental nickel-on-alumina In general, using high hydrogen content gases, part catalysts are produced by mixing together finely divided of the tail gas will be recycled, the remainder being nickel compound and finely divided alumina and pellet- 10 Withdrawn to prevent the build-up of inerts from reaching. Mixing may be carried out wet or dry and prefering an undesirably hlgh level. Preferred gas recycle ably by ball milling. rates (including make-up gas) lie in the range 300-700 B f use, the Supported elemental i k l catalyst s.c.f./b., preferably being about 500 standard cub1c feet as prepared above requires activation. This is conven- P berrel Of feedsleekiently carried out by heating the catalyst (e.g. in situ Typ hydrogen e0I1S11mPt 10I1 Yates lle 1n the range in the plant reactor) at 150 to 600 C. preferably about 60-140 Preferably belng ahout 250 C. in a stream of hydrogen or hydrogen containing Preferably the hydrogen abserptlon 1S controlled to gas, at a pressure in the range 0 to 200 p.s.i.g., for up t limit the loss of octane number (research clear) to bethree days. The temperature is preferably maintained at low it has been felled that, under these COHditIOIlS, 200-300 C. and the pressure at atmospheric. Wh the hydrogen absorption will lie in the range 50 to 150 the catalyst is prepared from nickel formate, activation Thus, according to a Preferred manner of may be carried out by heating at 150 C. 30() C i operation, the hydrogenation conditions are controlled an inert gas stream. After pre-treatment the catalyst will to maintain the hydrogen absorption rate Within this usually be pyrophoric. ran

P f bl catalysts employed in the process herein In general, the hydrogen treated product Wlll be stadescribed are Silicahea bilized, by distillation, to give a product of low 0.; con- If desh-gd hydrogenation may he carried out using tent, usually less than 1% by weight. The product may a gas consisting f hydrogen together with inert constim. also be re-run to establish desired end-point, for example, ents. Preferably, when inert constituents are present, an ASTM end 130mt of the gas contains at least 5 mol Percent f hydrogen, Spent catalyst may be pyrophoric and should be steam the proportion suitably lying within the range 25-90 mol purged before being dlscharged' Percent f hydrogen The invention is illustrated but in no way limited A preferred gas is a platformer tail gas. Suitably a with refei'ence to the foliowing examplesgas is employed containing 70 mol percent of hydrogen.

A typical gas will consist of 70 mol percent of hydrogen EXAMPLE 1 and 30 mol percent of methane. Other suitable gases Steam cracker gasoline of petroleum origin was passed are steam cracker ta1l gas, catalyst cracker tail gas and with hydrogen over a nickel-on-alumina catalyst containtall gas derived from the dehydrogenation of hydrocaring 10% by eigh of nick l. bons. 40 This gasoline before treatment had the following The hydrogenation may conveniently be carried out at Characteristics! a temperature in the range 0 to 200 C. and at a pressure in the range 0 to 1000 p.s.i.g. A suitable space Speclfic g y. Q7675 velocity is 1-6 vol./vol./hour for example 2 vol./vol./ i l g hour. Usually a vertical reactor, operating under downo C. 95.5 flow, s employed. F B P c C 19 Preferred operating pressures lie in the range 200-300 l u Sulphur content 0.007 lbs/sq. 1n. gauge. When using pressures in this range, Brdmine 63 1 gas mixtures having a hydrogen content of 50-90 mol. u I percent are very suitable. Thus a gas containing 50 Operating conditions and results obtained are shown mol percent of hydrogen can be used with advantage. in the following Table 1.

Table 1 Time on stream, hr Feed 0-3 3-48 48-50 5051 51-52 52-53 Temperature, C G4 102 116 152 160 Pressure. p.s.i.g 200 200 200 200 200 200 Feedrate,v./v./hr 1.92 1.98 1.81 1.87 2.05 Hg rate (approx), s.c.f./b 650 050 650 050 650 Recovery, percent weight.-- 98.9 Principal product data:

srlgtgilfisc 602F460:

0.7702 0 7625 0 7690 0.7655 0.7645 er en 1 a Gum existent ASTM), tti g./l00 1111.- I 0 9 0 0 0088 00081 Accelerated (120 min). mgJlOO m1 16 422 15 34 22 26 Accelerated (240 min), mg./100 m1... 129 16 38 39 9 Induction period: (ASTM), min 345 90 720 720 720 720 720 (11 mm 345 90 390 635 590 650 120 Bromine number 63.1 53.3 .7 Aromatics percent vol... 44.0 4 .0 FIA:

Oletines percent vol. 12.0 ,0 Saturates percent v0 44.0 .0 Diane index 4. 2 '& Octane number research (clear)... 93.0 .2

(+1.5 m1. TEL/1G) Lauson test mg. 3.25 USG (after ageing 20 days F.)

l Hard Gum.

EXAMPLE 2 Table 2 Time on stream, hr -3 3-48 48-50 Temperature, C. 86 101 98 Pressure. p.s.i.g 200 200 200 Feed rate. v./v./hr- 1. S0 1. 06 2.07 Gas rate, s.c.f./b 535 490 405 Hz absorption, s.e.f./b 333 135 122 Recovery, vol percent 84. S 102. 2 105. 0 Principal product data:

Specific gravity 60 F./60 F 0. 7650 0. 7070 0. 7095 Gum 1 existent (ASTM) rug/100 ml l1 -1 2 Accelerated (120 min), mg/lOO ml 19 2 6 Accelerated (240 min), IIlfI/IOO m1... 413 7 11 Induction period:

ASTM min 195 715 535 IP min 195 600 425 Bromine number 31. 4 50. 5 50. 7 Octane number clean. 86. 3 00. 0 90. 9 +1.5 rnl TEL/1G 94. 0 06. 0 96. 0

1 Hard Gntn.

Hydrogen absorption rates during the initial period (0-3 hours), are high. This results from the use of a freshly prepared catalyst and the values are thus not representative of steady running conditions.

EXAMPLE 3 Steam cracker gasoline, of petroleum origin, containing dienes and styrene homologues was passed with a hydrogen/ methane gas mixture, having a Bi /CH mol ratio of 1/ 3, over a nickel-omalumina catalyst containing 10% by weight of nickel. The gasoline had the characteristics shown in Table 3.

Operating conditions and results obtained were as shown in the following Table 4.

Table 4 Time on stream (hours) 0-3 3-6 Temperature, C .Q 100 133 Pressure, lbs/so. in. g 256 206 Feed rate, v./v./hr.. 1.03 0.98 Gas rate, s.e.f/bbl 1,770 1, 860 Hz absorption, s.o.f/bbl 1 50 Bromine number of product 52. 8 50. 8

EXAMPLE 4 Steam cracker gasoline of petroleum origin, as described in Example 3 was passed with a hydrogen/methane gas mixture over a nickel-on-alumina catalyst containing 10% by weight of nickel.

The gas mixture had the following composition in mol percent:

Hydrogen 61.1 Methane 37.4 Higher hydrocarbons 1.5

Operating conditions and results obtained are shown in the following Table 5.

Table 5 1 hr. 45 3 hr. 30 5 hr. 20 Time on stream 0-1 hrs. min. to min. to min. to

2 hr. 45 4 hr. 30 6 hr. 20

min. min. min.

]e1nperature 0. (average) 54 106 148 176 Pressure lbs/sq. in. gauge 202 203 202 202 Feed ate (m/v. r. 1. 71 2.02 1. 88 2. 22 Gas inlet rate (s.c.f./b.) 550 470 500 435 Hydrogen absorption s.c. b... 25 140 195 200 EXAMPLE 5 A catalyst consisting of nickel deposited on magnesium oxide was prepared in the following manner:

400 grams of magnesium oxide (commercial heavy grade passing E58 mesh) was mixed with 137 grams of nickel formate powder by sieving until homogeneous. The mixture was converted to A; (one-eighth inch) X A; (one-eighth inch) pellets and activated by treatment with hydrogen for four hours at 250 C.

Steam cnacker gasoline of petroleum origin was passed with hydrogen over the activated catalyst. The gasoline had the characteristics shown in Table 6; operating conditions and results obtained are shown in Table 7.

EXAMPLE 6 A catalyst consisting of nickel deposited on alumina was prepared in the following manner:

368 grams of alumina (commercial 6-12 888 mesh) was heated to 140 C. for 30 minutes. The hot alumina was impregnated with a solution of 200 grams nickel nitrate (hexahydrate) in 70 mls. of water and dried at 140 C. The impregnated alumina was roasted at 500 C. for two hours.

The roasted catalyst was activated by treatment with hydrogen at 500 C. for 16 hours.

Steam cracker gasoline of petroleum origin was passed with hydrogen over the activated catalyst using hydrogen recycle.

The pressure was maintained at lbs/sq. in. gauge; the hydrogen recycle rate was 500 s.c.f./bbl. and the liquid feed rate 2 vol./vol./hour.

The gasoline had the characteristics shown in Table 8; opening conditions and results obtained are shown in Table 9.

The product obtained during the period 710-750 hours was distilled with removal of 3% by wt. bottoms. Results specified are for the re-run product.

Table 8 Specific gravity 0.7755 ASTM distillation:

I.B.P., C. 44.0 50%, C. 105.0 90%, C. 164.0 F.B.P., c. 205.0 Sulphur content, percent weight 0.012 Bromine number 62.5 Total gum existent (ASTM), mg./100 ml 7 Total gum accelerated (120 min.), mg./ 100 ml. 18 Induction period:

ASTM (min.) 310 LP. (min.) 195 Octane number research clear 91.0 +1.5 ml. TEL/1G 94.9 Lauson test (aged) mg./3.25 U.S.G. 510

Table 9 Time on stream (hours) 10-109 110-209 210-310 610-710 710-750 Temperature (catalyst midbed) C.) 85 95 107 130 130 Average hydrogen absorption (s.c.f./bbl.) 72 05 73 96 110 Principal product data:

Specific gravity 7765 0.7745 0.7770 0.7785 0.7730 Total sulphur (percentwt.) 0. 014 0. 008 0.012 0. 014 0. 009 Gum existent (ASTM), mg./100 ml 4 1 8 3 7 Accelereted (120 min.) mg./

100 111 22 45 29 3 4 7 9 Induction period:

ASTM (min.) 570 335 405 535 390 IP (min.) 495 240 380 315 315 Bromine number 63.4 59. 5 58.7 57.9 55. 5 Octane number clear research 91. 2 91. 3 91. 0 90. 3 90. 5 +1.5 ml. TEL/IG 94. 7 9G. 0 96. 3 95. 1 95. 3 Lauson test (aged) mg./

3.25 USG 71 56 75 1 Re-run to 3% by Wt. bottoms. 2 Total gum. Hard gum. 4 Not determined.

EXAMPLE 7 The run described in Example 6 was continued for the period 760-1266 hours using a steam cracked gasoline of petroleum origin having the characteristics shown in Operating conditions and results obtained are shown in Table 11. The product obtained during the period 850-950 hours was distilled with removal of 3% by wt. bottoms. Results specified are for the re-run product.

8 Table 11 Time on steam (hours) 750-850 850-950 950-1, 0 1,050- 1,150-

Temperature (catalyst midbed) C.) 139 130 140 Average hydrogen absorp- 115 tion (s.c../bbl.) 97 91 93 102 Principal product data:

Specific gravity 0.7785 0.7725 0.7790 0.7780 0.7790 Total sulphur (percent weight) 0.009 0.007 0.012 0.012 0.010 Gum existent (ASTM mg./

640 335 005 720 720 I1 (min.) 450 225 290 390 630 Bromine number 54. 6 54. 3 53. 3 54.1 52. 7 Octane number clear research 90.8 90.9 91. 4 91.0 90.0 +1.5 ml. TEL/IG- 95. 7 95. 5 90.8 96.1 95.2 Lauson test (aged) mg./

3.25 USG 25 37 57 51 25 1 Re-run to 3% by wt. bottoms. 1 Hard gum.

We claim:

1. A process for improving a gasoline produced by cracking a petroleum fraction at a temperature above 1100 F. and containing at least one unsaturated hydrocarbon selected from the group consisting of diolefins and styrenes, which comprises passing said gasoline with hyydrogen over a supported elemental nickel catalyst under hydrogenation conditions of temperature in the range 0 to 200 C., pressure in the range 0-1000 p.s.i.'g. and space velocity in the range 1-6 vol./vol./hr., the hydrogenation conditions being selected within said ranges such that diolefins are hydrogenated to mono-olefins, and styrenes are hydrogenated to saturated side chain aromatics, without appreciable conversion of acyclic monoolefins to saturated hydrocarbons and without appreciable lessening of the octane number of the feedstock.

2. A process as specified in claim 1 in which the gasoline is of petroleum origin and boils within the range 15-200 C.

3. A process as specified in claim 1, in which the steam cracked gasoline has been produced by cracking at a temperature in the range 593-760 C. and at a pressure in the range 0-50 lbs/sq. in. gauge.

4. A process as specified in claim 3, in which the alumina is employed as gamma-alumina.

5. A process as specified in claim 1 in which the supported elemental nickel catalyst is an elemental nickelon-alumina catalyst.

6. A process as specified in claim 1 in which the gas employed for hydrogenation consists of hydrogen together with inert constituents.

7. A process as specified in claim 6, in which the gas contains at least 25 mol percent of hydrogen.

8. A process as specified in claim 7, in which the gas contains 25-90 mol percent of hydrogen.

9. A process as specified in claim 6, in which the gas is a platformer tail gas.

10. A process as specified in claim 6, in which the gas is a mixture consisting predominantly of a mixture of hydrogen and methane.

11. A process as specified in claim 1, in which the hydrogenation is carried out at a temperature in the range 80-180 C.

12. A process as specified in claim 1, in which the hydrogenation is carried out at a pressure in the range 200-300 lbs/sq. in. gauge.

13. A process as specified in claim 12, in which the gas used for hydrogenation contains inert constituents and 50-90 mol percent of hydrogen.

14. A process as specified in claim 13, in which the hydrogenation is carried out at a hydrogen partial pressure of at least 1001bs./sq. in. gauge.

15. A process as specified in claim 1, in which the hydrogenation is carried out with recycle of tail gas at a gas recycle rate in the range 300-700 s.c.f./b.

16. A process as specified in claim 1, in which the hydrogenation conditions are selected to give a hydrogen absorption per pass in the range 50-150 s.c.f./bbl.

17. A process as specified in claim 1, in which the gasoline has a total sulphur content in the range 0.005 to 0.04% by weight.

18. A process for improving a gasoline produced by cracking a petroleum fraction at a temperature above 1100 F. and containing acyclic mono-olefins and at least one unsaturated hydrocarbon selected from the group consisting of diolefins and styrenes, which comprises passing said gasoline with hydrogen over a supported elemental nickel catalyst under hydrogenation conditions of temperature in the range to 200 C., pressure in the range 0-1000 p.s.i.g. and space velocity in the range 1-6 vol./vol./hr., the hydrogenation conditions being selected within said ranges to provide a high percentage conversion of diolefins to mono-olefins, a high percentage conversion of styrenes to saturated side chain aromatics and a low percentage conversion of acyclic mono-olefins to saturated hydrocarbons Without appreciable lessening of the octane number of the feedstock.

19. A process for improving a gasoline produced by cracking a petroleum fraction at a temperature above 1100 F. and containing at least one unsaturated hydro carbon selected from the group consisting of diolefins and styrenes, which comprises continuously passing said gasoline with hydrogen over a supported elemental nickel catalyst under hydrogenation conditions of temperature in the range 0 to 200 C., pressure in the range 01000 p.s.i.g. and space velocity in the range l-6 vol./vol./hr., the hydrogenation conditions being selected within said ranges to fix the amount of hydrogen thereby combined with unit weight of the gasoline feedstock at an amount in the range -150 s.c.f./b. such that the octane number of the product is not substantially less than that of the gasoline feedstock.

References (Iited in the file of this patent UNITED STATES PATENTS 2,037,789 Ipatieif Apr. 21, 1936 2,073,578 Gwynn Mar. 9, 1937 2,638,438 Hoifmann et al May 12, 1953 2,901,423 Herbert et al Aug. 25, 1959 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3,024, 188 March 6, 1962 Alan Arthur Yeo et a1.

It is hereby certified that error appears in the above numbered pat ent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 19, for "improved" read improving column 3, line 37, for "catalyst" read catalytic column 7, Table 9, under the heading "Time on stream (hours)", line 11 thereof, for "Accelereted" read Accelerated column 8, Table 11, in the heading to column 1 thereof, for "Steam" read Stream same Table ll, heading to the fourth column, for

9so-1,0 d 950- 1,050 Pea 1,050

same table, last column, the second entry "115" should be dropped down one space so as to appear opposite 102", in the fifth column; same column 8, line 29, for "hyydrogen" read hydrogen Signed and sealed this 14th day of August 1962.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

1. A PROCESS FOR IMPROVING A GASOLINE PRODUCED BY CRACKING A PETROLEUM FRACTION AT A TEMPERATURE ABOVE 1100*F. AND CONTAINING AT LEAST ONE UNSATURATED HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF DIOLEFINS AND STYRENES, WHICH COMPRISES PASSING SAID GASOLINE WITH HYDROGEN OVER A SUPPORTED ELEMENTAL NICKEL CATALYST UNDER HYDROGENATION CONDITIONS OF TEMPERATURE IN THE RANGE 0* TO 200*C. PRESSURE IN THE RANGE 0-1000 P.S.I.G. AND SPACE VELOCITY IN THE RANGE 1-6 VOL/VOL/HR., THE HYDROGENATION CONDITIONS BEING SELECTED WITHIN SAID RANGES SUCH THAT DIOLEFINS ARE HYDROGENATED TO MONO-OLEFIMNS AND STYRENES ARE HYDROGENATED TO SATURED SIDE CHAIN AROMATICS, WITHOUT APPRECIABLE CONVERSION OF ACYCLIC MONOOLEFINS TO SATURATED HYDROCARBONS AND WITHOUT APPRECIABLE LESSENING OF THE OCTANE NUMBER OF THE FEEDSTOCK. 